Abstract: Provided are a biodegradable aliphatic-aromatic polyester copolymer having excellent hydrolysis resistance and high viscosity which has a carboxyl end group (CEG) content of 15 mg KOH/g or less, a ratio (Mz/Mn) of a z-average molecular weight (Mz) to a number average molecular weight (Mn) of 3 to 15, and a melt index (MI) of 5 g/10 min or less as measured under conditions of a temperature of 190° C. and a load of 2.16 kg in accordance with ASTM D 1238. A method of preparing a biodegradable aliphatic-aromatic polyester copolymer is provided, including adding a chain extender and an anti-hydrolysis agent to an aliphatic-aromatic polyester pre-copolymer over time, whereby a significant viscosity rise and improvement of hydrolysis resistance may be implemented simultaneously.

Abstract: Provided is a biodegradable polyester polymer comprising a polymerization reaction product of an aliphatic dicarboxylic acid, an C6-30 aromatic dicarboxylic acid, an aliphatic diol, and a branching agent, and wherein the biodegradable polyester polymer has a ratio of z-average molecular weight (Mz) to weight average molecular weight (Mw) (“Mz/Mw”) greater than 2 and an easy-tear film including the same. The biodegradable film has excellent mechanical properties to effectively protect a product inside the packaging but also be easily opened in a controlled manner without excessive force and at the same time, provide an environmentally-friendly alternative to non-degradable plastics.

Abstract: Provided are a biodegradable aliphatic-aromatic polyester copolymer having excellent hydrolysis resistance and high viscosity which has a carboxyl end group (CEG) content of 15 mg KOH/g or less, a ratio (Mz/Mn) of a z-average molecular weight (Mz) to a number average molecular weight (Mn) of 3 to 15, and a melt index (MI) of 5 g/10 min or less as measured under conditions of a temperature of 190° C. and a load of 2.16 kg in accordance with ASTM D 1238. A method of preparing a biodegradable aliphatic-aromatic polyester copolymer is provided, including adding a chain extender and an anti-hydrolysis agent to an aliphatic-aromatic polyester pre-copolymer over time, whereby a significant viscosity rise and improvement of hydrolysis resistance may be implemented simultaneously.

Abstract: A machine learning method for incremental learning builds a model by using training data and incrementally updates the built model by using only a new weight generated based on new training data.

Abstract: A method is provided for controlling the maximum access speed of an optical disc in an optical disc apparatus. If the optical disc loaded in the optical disc apparatus is a CD-R having a possibility of creating many errors during the data reading/writing process, the maximum access speed can be changed according to disc maker information or user's request. As a result, the optical disc apparatus can stably record or reproduce data on/from a specific optical disc such as a CD-R, and does not decelerate unnecessarily the maximum access speed of a high-quality optical disc providing superior data reading/writing performance.